Shunted multiple throw MEMS RF switch

• US 6,570,750 B1
• Filed: 04/19/2000
• Issued: 05/27/2003
• Est. Priority Date: 04/19/2000
• Status: Expired due to Term

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Inventors: Strawser, Richard E., Lesniak, Christopher D., Calcatera, Mark C.
• Primary Examiner(s): Jackson, Stephen W.
• Application Number:
  US09/552,030
• Time in Patent Office: 1,133 Days
• Field of Search: 361/212, 361/115, 361/58, 361/234, 361/220, 361/160, 361/152, 361/113
• US Class Current: 361/115
• CPC Class Codes: H01G 5/18 due to change in inclination, e.g. by flexing, by spiral wrapping
• CPC Class Codes: H01G 5/40 Structural combinations of variable capacitors with other electric elements not covered by this subclass, the structure mainly consisting of a capacitor, e.g. RC combinations
• CPC Class Codes: H01H 2059/0027 Movable electrode connected to ground in the open position, for improving isolation
• CPC Class Codes: H01H 59/0009 making use of micromechanics
• CPC Class Codes: H01P 1/127 Strip line switches

Abstract

A micromechanical electrical systems (MEMS) metallic micromachined multiple ported electrical switch receivable on the die of an integrated circuit and within the integrated circuit package for controlling radio frequency signal paths among a plurality of switch-enabled different path choices. The switch provides desirably small signal losses in both the switch open and switch closed conditions. The switch is primarily of the single pole multiple throw mechanical type with possible use as a single input pole, multiple output poles device and provision for grounding open nodes in the interest of limiting capacitance coupling across the switch in its open condition. Cantilever beam switch element suspension is included along with normally open and normally closed switch embodiments, electrostatic switch actuation and signal coupling through the closed switch by way of increased inter electrode capacitance coupling. Switch operation from direct current to a frequency above ten gigahertz is accommodated.

Claims

1. Normally open multiple ported integrated circuit radio frequency transmission line metallic mechanical electrical switching apparatus comprising the combination of:

an integrated circuit substrate member;

a plurality of semiconductor material layers disposed on said substrate member, said semiconductor material layers comprising a plurality of electrical transistor members;

an array of spaced apart metallic transmission line ground member elements residing on an upper surface portion of said semiconductor material layers;

a metallic first radio frequency energy transmission line signal conveying member disposed intermediate elements of said metallic transmission line ground member array on said upper surface portion of said semiconductor material layers;

said metallic first radio frequency energy transmission line signal conveying member interconnecting a switch contact area on said surface portion of said semiconductor material layers with one of a transmission line radio frequency source and load member;

a second metallic radio frequency energy transmission line signal conveying member disposed intermediate elements of said metallic transmission line ground member array on said upper surface portion of said semiconductor material layers;

a third metallic radio frequency energy transmission line signal conveying member disposed intermediate elements of said metallic transmission line ground member array on said upper surface portion of said semiconductor material layers;

said second and third metallic radio frequency energy transmission line signal conveying members each including a selectively movable portion extending in segregated overlap over a part of said first metallic radio frequency energy transmission line signal conveying member and normally resident in open switch spring biased physical segregation from said metallic first radio frequency energy transmission line signal conveying member and said upper surface portion of said semiconductor material layers and said substrate member;

said second and third metallic radio frequency energy transmission line signal conveying members being individually movable into positions of close intimate spacing with respect to said first metallic radio frequency energy transmission line signal conveying member during individual energized, closed switch operating conditions;

a raised metallic backstop member extending from one of said metallic transmission line ground members over said selectively movable portions of said second and third radio frequency energy transmission line signal conveying members;

said backstop member being engaged by and grounding said selectively movable portions of said second and third metallic radio frequency energy transmission line signal conveying members in said spring biased open switch condition thereof;

first electrostatic force generating electrical potential apparatus connected between said first metallic radio frequency energy transmission line signal conveying member and said second metallic radio frequency energy transmission line signal conveying member and selectively generating an electrical potential achieving said individual energized, closed switch operating condition of said second metallic radio frequency energy transmission line signal conveying member;

second electrostatic force generating electrical potential apparatus connected between said first metallic radio frequency energy transmission line signal conveying member and said third metallic radio frequency energy transmission line signal conveying member and selectively generating an electrical potential achieving said individual energized, closed switch operating condition of said third metallic radio frequency energy transmission line signal conveying member.

2. The normally open multiple ported integrated circuit radio frequency transmission line metallic mechanical electrical switching apparatus of claim 1 wherein said first and second electrostatic force generating electrical potential apparatus comprise a source of direct current electrical bias summed with a source of said radio frequency energy.

3. The normally open multiple ported integrated circuit radio frequency transmission line metallic mechanical electrical switching apparatus of claim 1 wherein said substrate member and said semiconductor material layers are comprised of one of the materials of silicon and gallium arsenide.

4. The normally open multiple ported integrated circuit radio frequency transmission line metallic mechanical electrical switching apparatus of claim 1 wherein said metallic transmission line ground members and said metallic first, second and third radio frequency energy transmission line signal conveying members comprise coplanar transmission line elements.

5. The normally open multiple ported integrated circuit radio frequency transmission line metallic mechanical electrical switching apparatus of claim 1 wherein one of said movable second and third metallic radio frequency energy transmission line signal conveying members is connected with a radio frequency energy load member.

6. The normally open multiple ported integrated circuit radio frequency transmission line metallic mechanical electrical switching apparatus of claim 1 wherein said movable second and third metallic radio frequency energy transmission line signal conveying members are orthogonally disposed with respect to said first radio frequency energy transmission line signal conveying member in said upper surface portion of said semiconductor material layers.

7. The normally open multiple ported integrated circuit radio frequency transmission line metallic mechanical electrical switching apparatus of claim 1 wherein each of said first and second electrostatic force generating electrical potential apparatus generate an electrical potential of less than twenty five volts.

8. The normally open multiple ported integrated circuit radio frequency transmission line metallic mechanical electrical switching apparatus of claim 1 wherein said energized, closed switch operating condition position of close intimate spacing between each of said movable second and third metallic radio frequency energy transmission line signal conveying members and said first metallic radio frequency energy transmission line signal conveying member has a capacitance fifty to one hundred times greater than an open switch condition.

9. Metallic mechanical integrated circuit radio frequency transmission line electrical switching apparatus comprising the combination of:

an integrated circuit substrate member;

a plurality of semiconductor material layers disposed on said substrate member, said semiconductor material layers comprising a plurality of electrical transistor members;

an array of spaced apart metallic transmission line ground member elements residing on an upper surface portion of said semiconductor material layers;

a metallic first radio frequency energy transmission line signal conveying member disposed intermediate elements of said metallic transmission line ground member array on said upper surface portion of said semiconductor material layers;

said metallic first radio frequency energy transmission line signal conveying member interconnecting a switch overlap area on said surface portion of said semiconductor material layers with one of a transmission line radio frequency source and load members;

a metallic second radio frequency energy transmission line signal conveying member disposed intermediate elements of said metallic transmission line ground member array on said upper surface portion of said semiconductor material layers;

a metallic third radio frequency energy transmission line signal conveying member disposed intermediate elements of said metallic transmission line ground member array on said upper surface portion of said semiconductor material layers;

said second and third metallic radio frequency energy transmission line signal conveying members each including a selectively movable portion overlapping segregated portions of said first metallic radio frequency energy transmission line signal conveying member in said overlap area;

a metallic bridge member extending upward over said selectively movable portions of said second and third metallic radio frequency energy transmission line signal conveying members in said overlap area from one of;

said first metallic radio frequency energy transmission line signal conveying member; and

one of said metallic transmission line ground member elements;

said second and third metallic radio frequency energy transmission line signal conveying members each being normally resident in one of;

open switch relaxed spring physical segregation from said upper surface portion of said semiconductor material layers and said substrate member and interconnected via said metallic bridge member with one of said metallic transmission line ground member elements; and

closed switch relaxed spring physical segregation from said upper surface portion of said semiconductor material layers and said substrate member in close intimate spaced coupling with said first radio frequency energy transmission line signal conveying member via said metallic bridge member;

first electrostatic force generating electrical potential apparatus connected between said first metallic radio frequency energy transmission line signal conveying member and said second metallic radio frequency energy transmission line signal conveying member and selectively generating an electrical potential achieving an energized, closed switch operating condition of said second metallic radio frequency energy transmission line signal conveying member with said first radio frequency energy transmission line signal conveying member;

second electrostatic force generating electrical potential apparatus connected between said first metallic radio frequency energy transmission line signal conveying member and said third metallic radio frequency energy transmission line signal conveying member and selectively generating an electrical potential achieving an energized closed switch operating condition of said third metallic radio frequency energy transmission line signal conveying member with said first radio frequency energy transmission line signal conveying member.

10. The metallic mechanical integrated circuit radio frequency transmission line electrical switching apparatus of claim 9 wherein said switching apparatus comprises a normally open electrical switch and wherein:

said metallic bridge member extending upward over said selectively movable portions of said second and third metallic radio frequency energy transmission line signal conveying members extends from one of said metallic transmission line ground member elements;

said second and third metallic radio frequency energy transmission line signal conveying members are each normally resident in open switch relaxed spring physical segregation from said upper surface portion of said semiconductor material layers and said substrate member proximate said metallic bridge member.

11. The metallic mechanical integrated circuit radio frequency transmission line electrical switching apparatus of claim 9 wherein said switching apparatus comprises a normally closed electrical switch and wherein:

said metallic bridge member extending upward over said selectively movable portions of said second and third metallic radio frequency energy transmission line signal conveying members extends from said first metallic radio frequency energy transmission line signal conveying member; and

said second and third metallic radio frequency energy transmission line signal conveying members are each normally resident in closed switch relaxed spring physical segregation from a ground plane element resident thereunder on said upper surface portion of said semiconductor material layers and said substrate member and proximate said metallic bridge member.

12. The metallic mechanical integrated circuit radio frequency transmission line electrical switching apparatus of claim 9 further including:

a metallic fourth radio frequency energy transmission line signal conveying member disposed intermediate elements of said metallic transmission line ground member array on said upper surface portion of said semiconductor material layers;

said fourth metallic radio frequency energy transmission line signal conveying member including a selectively movable portion overlapping segregated portions of said first metallic radio frequency energy transmission line signal conveying member in said overlap area; and

a third of said electrostatic force generating electrical potential apparatus.

13. The metallic mechanical integrated circuit radio frequency transmission line electrical switching apparatus of claim 9 wherein:

said first metallic radio frequency energy transmission line signal conveying member is a switch input node member;

said first metallic radio frequency energy transmission line signal conveying member interconnects with a transmission line radio frequency source; and

said second and third metallic radio frequency energy transmission line signal conveying members are switch output node members each interconnected with a transmission line radio frequency load.

14. The method of performing electrical switching in a metallic conductor signal path of a radio frequency integrated circuit electrical device, said method comprising the steps of:

disposing an electrical switching assembly at an angular junction multiple conductor fan-out position along a metallic transmission line signal path in said radio frequency integrated circuit electrical device;

holding a spring urged movable metallic portion of each conductor in said multiple conductor fan-out position of said electrical switching assembly in a relaxed minimal spring tension first switching condition during quiescent state intervals of said electrical switching assembly;

changing one spring urged movable metallic conductor portion in said multiple conductor fan-out position of said electrical switching assembly into a stressed greater spring tension transient state second switching condition during selected transient actuated switch operating intervals of said electrical switching assembly;

changing said movable metallic conductor portion switching position against spring tension into said stressed greater spring tension transient state second switching condition using electrostatic force generated by an electrical potential switch control signal;

limiting spring tension urged movable metallic conductor movement arc length and movable metallic conductor element spacing gap in said electrical switching assembly during a relaxation from said second switching condition to said first switching condition using a metal stopping member selectively disposed along a switch position-changing swing path of said movable metallic conductor;

coupling radio frequency electrical signal between said movable metallic conductor-electrical switching member and a switch output conductor member using one of capacitance and ohmic coupling between said switching member and a switch output conductor member in one of said first and second switching conditions;

limiting capacitance electrical signal coupling between said movable metallic conductor electrical switching member and said switch output conductor member by one of capacitance coupled and ohmic contact grounding of said movable metallic conductor electrical switching member to a zero electrical potential metal stopping member in a remaining of said first and second switching conditions;

said first and second switching conditions comprising one of;

a normally open condition in said electrical switching assembly including lowest capacity coupling between said movable metallic conductor electrical switching member and said switch output conductor member plus concurrent grounding by one of capacitance coupled and ohmic contact grounding of said movable metallic conductor member to said zero electrical potential metal stopping member; and

a normally closed condition in said electrical switching assembly including greatest capacity coupling between said movable metallic conductor electrical switching member and said switch output conductor member plus actuated switch grounding by one of capacitance coupled and ohmic contact grounding of said movable metallic conductor member to said zero electrical potential metal stopping member;

repeating said step of changing one spring urged movable metallic conductor portion in said multiple conductor fan-out position of said electrical switching assembly into a stressed greater spring tension transient state second switching condition using a selected one of said spring urged movable metallic conductor portions.

15. The method of performing electrical switching in a metallic conductor path of a radio frequency integrated circuit electrical device metallic conductor of claim 14 wherein:

said movable metallic conductor-inclusive electrical switching member quiescently resides in a normally open electrical switching condition;

said step of limiting spring tension urged movable metallic conductor movement arc and switch element spacing gap includes spring tension urging of said movable metallic conductor away from said switch output conductor member into proximity with an overhanging grounding potential metal stopping member while entering said normally open electrical switching condition.

16. The method of performing electrical switching in a metallic conductor path of a radio frequency integrated circuit electrical device metallic conductor of claim 14 wherein:

said movable metallic conductor-inclusive electrical switching member quiescently resides in a normally closed electrical switching condition;

said step of limiting spring tension urged movable metallic conductor movement arc and switch element spacing gap includes spring tension urging of said movable metallic conductor away from a grounding electrical stop member and into proximity with an overhanging location of said switch output conductor member while entering said normally closed electrical switching condition.

17. The method of performing electrical switching in a metallic conductor path of a radio frequency integrated circuit electrical device metallic conductor of claim 14 wherein a first of said movable metallic conductor electrical switching member and said switch output conductor member comprises a source of radio frequency energy and a second of said members comprises a radio frequency load connection and wherein said step of limiting capacitance-accomplished electrical signal coupling comprises one of the steps of shunt loading said source of radio frequency energy and shunt paralleling a signal load member.

18. The method of performing electrical switching in a metallic conductor path of a radio frequency integrated circuit electrical device metallic conductor of claim 14 further including the step of operating said integrated circuit electrical device at an operating frequency in the range of direct current to greater than ten gigahertz.

19. The method of performing ohmic electrical switching in a metallic conductor signal path of a radio frequency integrated circuit electrical device, said method comprising the steps of:

disposing an electrical switching assembly at an angular junction multiple conductor fan-out position along a metallic transmission line signal path in said radio frequency integrated circuit electrical device;

holding a spring urged movable metallic portion of each conductor in said multiple conductor fan-out position of said electrical switching assembly in a relaxed minimal spring tension first switching condition during quiescent state intervals of said electrical switching assembly;

changing one spring urged movable metallic conductor portion in said multiple conductor fan-out position of said electrical switching assembly into a stressed greater spring tension transient state second switching condition during selected transient actuated switch operating intervals of said electrical switching assembly;

changing said movable metallic conductor portion switching position against spring tension into said stressed greater spring tension transient state second switching condition using electrostatic force generated by an electrical potential switch control signal;

limiting spring tension urged movable metallic conductor movement arc length and movable metallic conductor element spacing gap in said electrical switching assembly during a relaxation from said second switching condition to said first switching condition using a metal stopping member selectively disposed along a switch position-changing swing path of said movable metallic conductor;

coupling radio frequency electrical signal between said movable metallic conductor-electrical switching member and a switch output conductor member using ohmic contact coupling achieved between said switching member and a switch output conductor member in one of said first and second switching conditions;

limiting capacitance electrical signal coupling between said movable metallic conductor electrical switching member and said switch output conductor member by ohmic connection grounding of said movable metallic conductor electrical switching member to a zero electrical potential metal stopping member in a remaining of said first and second switching conditions;

said first and second switching conditions comprising one of;

a normally open condition in said electrical switching assembly including lowest capacity coupling between said movable metallic conductor electrical switching member and said switch output conductor member plus concurrent ohmic connection grounding of said movable metallic conductor member to said zero electrical potential metal stopping member; and

a normally closed condition in said electrical switching assembly including ohmic connection grounding of said movable metallic conductor member to said zero electrical potential metal stopping member;

repeating said step of changing one spring urged movable metallic conductor portion in said multiple conductor fan-out position of said electrical switching assembly into a stressed greater spring tension transient state second switching condition using a selected one of said spring urged movable metallic conductor portions.